This website uses cookies to deliver some of our products and services as well as for analytics and to provide you a more personalized experience. Click here to learn more. By continuing to use this site, you agree to our use of cookies. We've also updated our Privacy Notice. Click here to see what's new.

This website uses cookies to deliver some of our products and services as well as for analytics and to provide you a more personalized experience. Click here to learn more. By continuing to use this site, you agree to our use of cookies. We've also updated our Privacy Notice. Click here to see what's new.

About Optics & Photonics TopicsOSA Publishing developed the Optics and Photonics Topics to help organize its diverse content more accurately by topic area. This topic browser contains over 2400 terms and is organized in a three-level hierarchy. Read more.

Topics can be refined further in the search results. The Topic facet will reveal the high-level topics associated with the articles returned in the search results.

Abstract

We consider the design of optical systems capable of providing near 100% absorption of visible light, consisting of a structured thin layer of a weakly absorbing semiconductor placed on top of a dielectric spacer layer and a metallic mirror layer. We generalise a system recently studied semi-analytically and experimentally by Stürmberg et al [Optica 3, 556 2016] which incorporated a grating layer of antimony sulphide and delivered high, narrow-band absorptance of normally-incident light for a single polarisation. We demonstrate that bi-periodic gratings can be optimised to deliver near–perfect absorptance of unpolarised light in the system, and comment on the wavelength and angular ranges over which the absorptance remains near 100%. We show that the properties of the systems studied depend on the interaction of multiple modes, and cannot be accurately modelled within the quasistatic approximation.

Figures (15)

Fig. 1 Schematic representation of the system consisting of a silver substrate, homogeneous layer of SiO2 with thickness t, and a grating with two-dimensional periodicity (period D in both x and y-directions) and height H which is made of a matrix substance 1 and cylindrical holes made of material 2 (specified in Table 1). The incident direction is specified by two angles, the polar angle ϕ between the incident wavevector and the normal to the surface (z-axis), and the azimuthal angle ψ between the projection
k‖i of ki on the xy-plane. The polarization of the incident wave is kept perpendicular to the xz-plane..

Fig. 2 (Left) Reflectance (black, left scale) and absorptance (red, right scale) in the silver layer of the grating structure of Case 1, Table 1, as a function of wavelength. Full lines - exact values, dots - taking into account the single order (0, 0) inside the SiO2 homogeneous layer. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β. The electric field of the incident plane wave is along the β axis.

Fig. 4 (Left) Reflectance for the structure of Case 7, Table 1 at a wavelength (0.540 μm) near the first minimum of normal reflectance as a function of dimensionless direction cosines α and β. (Right) As at left, but for the second minimum wavelength (0.591 μm) of normal reflectance.

Fig. 5 Scattered field components just above the surface of the biperioidc grating, as a function of position (x, y), for the first minimum wavelength (0.5557 μm) of total reflectance. The black dotted lines represent the cylinders made of antimony sulfide.

Fig. 7 Total electric field components with respect to z (in μm), in the direction perpendicular to the layers, for x = y = 0. (Left) First minimum wavelength (0.5557 μm) of total reflectance. (Right) Second minimum wavelength (0.591 μm) of total reflectance. The black dotted lines represent the layers interfaces from the substrate (bottom) to the superstrate (top).

Fig. 8 (Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 2, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 9 (Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 3, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 10 (Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 4, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 11 (Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 5, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 12 (Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 6, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 13 (Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 8, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 14 (Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 9, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 15 (Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 10, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Metrics

Table 1

The parameters of the 10 optimised doubly-periodic absorber systems: lattice type, constituents (1 for the matrix, 2 for the inclusion), spacer thickness, cylinder diameter, cylinder length, reflectance at the design wavelength and flux into the silver substrate. Distances in μm.